Use Of Polytetrahydrofurans In Lubricating Oil Compositions

ABSTRACT

An axle lubricating oil composition includes a polyalphaolefin having a kinematic viscosity at 100° C. of from 2 to 40 cSt when measured in accordance with ASTM D445. The axle lubricating oil composition also includes an alkoxylated polytetrahydrofuran of general formula (II). The alkoxylated polytetrahydrofuran of general formula (II) is present in an amount of from 10 to 40 parts by weight based on 100 parts by weight of the axle lubricating oil composition.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of Ser. No. 14/890,746, which is the U.S. National Stage of International Application No. PCT/EP2014/059276 filed on May 7, 2014, which claims priority to European Application No. 13168334 filed on May 17, 2013.

FIELD OF THE INVENTION

The present invention generally relates to the use of polytetrahydrofurans that are prepared by alkoxylating polytetrahydrofuran with at least one C₈-C₃₀ epoxy alkane in lubricating oil compositions, including axle lubricating oil compositions.

BACKGROUND OF THE INVENTION

Lubricating oil compositions are used in a variety of applications, such as industrial applications, transportation and engines. Industrial applications comprise of applications such as hydraulic oil, air compressor oil, gas compressor oil, gear oil, bearing and circulating system oil, refrigerator compressor oil and steam and gas turbine oils.

Conventional lubricating oil compositions comprise base stocks, co-solvents and additives. The base stock is in each case selected according to the viscosity that is desired in the envisioned application. Combinations of base stocks of different viscosities, i.e. low and high viscosity respectively, are often used to adjust the needed final viscosity. The co-solvents are used to dissolve polar additives in usually less polar or unpolar base stocks.

The most common additives are antioxidants, detergents, anti-wear additives, metal deactivator, corrosion inhibitors, friction modifiers, extreme-pressure additives, defoamers, anti-foaming agents, viscosity index improvers and demulsifying agents. These additives are used to impart further advantageous properties to the lubricating oil composition including longer stability and additional protection.

However, after a certain operation time, lubricating oil compositions have to be replaced for various reasons such as lubricity loss and/or product degradation. Depending on the machine (engine, gearbox, compressor . . . ) engineering design and the affinity of the lubricant components to adhere to the surface, a certain residue of the lubricating oil composition (hold-up) remains in the machine, engine, gear etc. It is used in. When being replaced by an unused and possibly different lubricating oil composition, the used and new lubricants are mixed with each other. Thus, in order to avoid any complications during operation, compatibility between the old and new lubricant is very important.

Depending on their chemical properties a variety of components of lubricating oil compositions are incompatible with each other, i.e. the mixture of these components leads to oil gelling, phase separation, solidifying or foaming. The oil gelling leads to a dramatic increase of the viscosity which in turn can cause engine problems and can even require the engine to be replaced, if the damage is severe. Hence, when providing novel compounds that are used in lubricating oil compositions it should always be ensured that these compounds are compatible with compounds that are conventionally used in lubricating oil compositions.

Besides compatibility with other lubricants, another area of concern is the energy efficiency. The efficiency can be increased if losses are minimized. The losses can be categorized in losses without and with load, their sum being the total losses. Within many parameters which can be influenced by geometry, material etc. lubricant viscosity has a major effect on losses without load, i.e. spilling: Losses with load can be influenced by a low friction coefficient. Thus, at a given viscosity, energy efficiency strongly depends on the friction coefficient measured for a lubricant.

The friction coefficient can be measured with several methods like Mini-Traction-Machine (MTM), SRV, 2 disc test rig etc. The benefit of a MTM is that one can see the coefficient of friction as an influence of the slide roll ratio. Slide roll ratio describes the difference of the speeds of ball and disc used in the MTM.

DE 32 10 283 A1 describes polyethers that are obtained by reacting C8-C28-epoxy alkane and tetrahydrofuran in the presence of a starter compound having Zerewitinoff-active hydrogen atoms. These compounds show lubricating properties.

EP 1 076 072 A1 discloses polyethers derived from polytetrahydrofuran and mixtures of 1,2-epoxybutane and 1,2-epoxydodecane. These compounds are formulated into gasoline fuels to reduce the deposits in an injector.

Thus, there remains an opportunity to provide compounds that show a low friction coefficient and that are compatible with base stocks, in particular base stocks such as mineral oils and polyalphaolefins, which are conventionally used in lubricating oil compositions and axle lubricating oil compositions.

SUMMARY OF THE INVENTION AND ADVANTAGES

The present invention provides an axle lubricating oil composition. The axle lubricating oil composition comprises a polyalphaolefin having a kinematic viscosity at 100° C. of from 2 to 40 cSt when measured in accordance with ASTM D445. The axle lubricating oil composition also includes an alkoxylated polytetrahydrofuran of general formula (II) present in an amount of from 10 to 40 parts by weight based on 100 parts by weight of said axle lubricating oil composition:

Wherein: m is an integer in the range of ≧1 to ≦50; m′ is an integer in the range of ≧1 to ≦50; (m+m′) is an integer in the range of ≧1 to ≦90; n is an integer in the range of ≧0 to ≦75; n′ is an integer in the range of ≧0 to ≦75; p is an integer in the range of ≧0 to ≦75; p′ is an integer in the range of ≧0 to ≦75; k is an integer in the range of ≧2 to ≦30; R¹ denotes an unsubstituted, linear or branched, alkyl radical having 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27 or 28 carbon atoms; R² denotes —CH₂—CH₃; and R³ is identical or different and denotes a hydrogen atom or —CH₃. With the concatenations denoted by k are distributed to form a block polymeric structure and the concatenations denoted by p, p′, n, n′, m and m′ are distributed to form a block polymeric structure or a random polymeric structure. In certain embodiments, the polyalphaolefin is present in an amount of from 20 to 60 parts by weight based on 100 parts by weight of the axle lubricating oil composition. Similarly, in certain embodiments, the axle lubricating oil composition has a KRL Shear loss after 200 hours of less than 8% when measured in accordance with CEC L-45-A-99.

Surprisingly, it has been found that alkoxylated polytetrahydrofurans which are derived from polytetrahydrofuran and at least one C₈-C₃₀ epoxy alkane show a low friction coefficient and are compatible with base stocks that are conventionally used in lubricating oil compositions such as mineral oils and polyalphaolefins, preferably low viscosity polyalphaolefins, and consequently can be used for the formulation of lubricating oil compositions. In addition, the alkoxylated polytetrahydrofurans which are derived from polytetrahydrofuran and at least one C₈-C₃₀ epoxy alkane may be used for the formulation of lubricating oil compositions, including axle lubricating oil compositions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a line graph illustrating friction coefficient data for an embodiment of the axle lubricating oil composition.

FIG. 2A is a bar graph illustrating fuel efficiency data for another embodiment of the axle lubricating oil composition.

FIG. 2B is another bar graph illustrating fuel efficiency data for the axle lubricating oil composition of FIG. 2A.

FIG. 2C is another bar graph illustrating fuel efficiency data for the axle lubricating oil composition of FIGS. 2A and 2B.

DETAILED DESCRIPTION OF THE INVENTION

Hence, in one embodiment, the presently claimed invention is directed to the use of an alkoxylated polytetrahydrofuran of general formula (I)

Wherein:

m is an integer in the range of ≧0 to ≦30,

m′ is an integer in the range of ≧0 to ≦30,

(m+m′) is an integer in the range of ≧1 to ≦60,

k is an integer in the range of ≧2 to ≦30, and

R1 denotes an unsubstituted, linear or branched, alkyl radical having 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27 or 28 carbon atoms, whereby the concatenations denoted by k, m and m′ are distributed to form a block polymeric structure, as lubricant.

Hence, in another embodiment, the presently claimed invention is directed to the use of an alkoxylated polytetrahydrofuran of general formula (II)

Wherein:

m is an integer in the range of ≧1 to ≦50,

m′ is an integer in the range of ≧1 to ≦50,

(m+m′) is an integer in the range of ≧1 to ≦90,

n is an integer in the range of ≧0 to ≦75,

n′ is an integer in the range of ≧0 to ≦75,

p is an integer in the range of ≧0 to ≦75,

p′ is an integer in the range of ≧0 to ≦75,

R1 denotes an unsubstituted, linear or branched, alkyl radical having 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27 or 28 carbon atoms,

R2 denotes —CH2-CH3, and

R3 identical or different, denotes a hydrogen atom or —CH3,

whereby the concatenations denoted by k are distributed to form a block polymeric structure and the concatenations denoted by p, p′, n, n′, m and m′ are distributed to form a block polymeric structure or a random polymeric structure, as lubricant.

Hence, in another embodiment, the presently claimed invention is directed to the use of an alkoxylated polytetrahydrofuran of general formula (II)

wherein

m is an integer in the range of ≧1 to ≦30,

m′ is an integer in the range of ≧1 to ≦30,

(m+m′) is an integer in the range of ≧2 to ≦60,

n is an integer in the range of ≧0 to ≦45,

n′ is an integer in the range of ≧0 to ≦45,

(n+n′) is an integer in the range of ≧0 to ≦80,

p is an integer in the range of ≧0 to ≦25,

p′ is an integer in the range of ≧0 to ≦25,

(p+p′) is an integer in the range of ≧0 to ≦30,

k is an integer in the range of ≧2 to ≦30,

R1 denotes an unsubstituted, linear or branched, alkyl radical having 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27 or 28 carbon atoms,

R2 denotes —CH2-CH3, and

R3 identical or different, denotes a hydrogen atom or —CH3,

whereby the concatenations denoted by k are distributed to form a block polymeric structure and the concatenations denoted by p, p′, n, n′, m and m′ are distributed to form a block polymeric structure or a random polymeric structure, as lubricant.

Hence, in another embodiment, the presently claimed invention is directed to the use of an alkoxylated polytetrahydrofuran of general formula (II)

wherein

m is an integer in the range of ≧1 to ≦50,

m′ is an integer in the range of ≧1 to ≦50,

(m+m′) is an integer in the range of ≧1 to ≦90,

n is an integer in the range of ≧0 to ≦75,

n′ is an integer in the range of ≧0 to ≦75,

p is an integer in the range of ≧0 to ≦75,

p′ is an integer in the range of ≧0 to ≦75,

R1 denotes an unsubstituted, linear or branched, alkyl radical having 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27 or 28 carbon atoms,

R2 denotes —CH2-CH3, and

R3 identical or different, denotes a hydrogen atom or —CH3,

whereby the concatenations denoted by k are distributed to form a block polymeric structure and the concatenations denoted by p, p′, n, n′, m and m′ are distributed to form a block polymeric structure or a random polymeric structure, for reducing friction between moving surfaces, whereby friction is determined by measuring the friction coefficient at 25% slide roll ratio (SRR) using mini-traction machine (MTM) measurements at 70° C. and 1 GPa.

By the term of “lubricant”, in the sense of the presently claimed invention, is meant a substance capable of reducing friction between surfaces.

As used herein, “branched” denotes a chain of atoms with one or more side chains attached to it. Branching occurs by the replacement of a substituent, e.g., a hydrogen atom, with a covalently bonded alkyl radical.

“Alkyl radical” denotes a moiety constituted solely of atoms of carbon and of hydrogen.

Alkoxylated polytetrahydrofurans are inter alia described in U.S. Pat. No. 6,423,107 B1. However, this patent is entirely silent about using alkoxylated polytetrahydrofurans as lubricants.

The inventively claimed alkoxylated polytetrahydrofurans are oil soluble, which means that, when mixed with mineral oils and/or polyalphaolefins, preferably low viscosity polyalphaolefins, in a weight ratio of 10:90, 50:50 and 90:10, the inventively claimed alkoxylated polytetrahydrofurans do not show phase separation after standing for 24 hours at room temperature for at least two weight ratios out of the three weight ratios 10:90, 50:50 and 90:10. Preferably the alkoxylated polytetrahydrofuran has a kinematic viscosity in the range of ≧200 mm2/s to ≦1,200 mm2/s, ≧200 mm2/s to ≦700 mm2/s, or more preferably in the range of ≧250 mm2/s to ≦650 mm2/s, at 40° C. and determined according to ASTM D 445. In one embodiment, the alkoxylated polytetrahydrofuran has a kinematic viscosity in the range of ≧250 mm2/s to ≦1100 mm2/s at 40° C. and determined according to ASTM D 445.

Preferably the alkoxylated polytetrahydrofuran has a kinematic viscosity in the range of ≧25 mm2/s to ≦150 mm2/s, ≧25 mm2/s to ≦90 mm2/s, or more preferably in the range of ≧30 mm2/s to ≦80 mm2/s, at 100° C., determined according to ASTM D 445. In one embodiment, the alkoxylated polytetrahydrofuran has a kinematic viscosity in the range of ≧30 mm2/s to ≦130 mm2/s, at 100° C. and determined according to ASTM D 445.

Preferably the alkoxylated polytetrahydrofuran has a pour point in the range of ≧−60° C. to ≦20° C., more preferably in the range of ≧−50° C. to ≦15° C., determined according to DIN ISO 3016.

Preferably the alkoxylated polytetrahydrofuran has a weight average molecular weight Mw in the range of 500 to 20000 g/mol, more preferably in the range of 2000 to 10000 g/mol, most preferably in the range of 2000 to 7000 g/mol, even more preferably in the range of 4000 to 7000 g/mol determined, determined according to DIN 55672-1. For the purpose of this disclosure, any reference to weight average molecular weight determined according to DIN 55672-1 is measured by gel permeation chromatography with reactive index detection using the following: a polystyrene calibration, 2×PL gel 300×7.5 mm, 3 μm columns from Agilent, a mobile phase of tetrahydrofurane, a flow rate of 1.0 ml/min, an injection volume of 100 μl, and a temperature of 35° C.

Preferably the alkoxylated polytetrahydrofuran has a polydispersity in the range of 1.05 to 1.60, more preferably in the range of 1.05 to 1.50, most preferably in the range of 1.05 to 1.45, determined according to DIN 55672-1.

Preferably k is an integer in the range of ≧3 to ≦25, more preferably k is an integer in the range of ≧3 to ≦20, most preferably in the range of ≧5 to ≦20, even more preferably in the range of ≧6 to ≦16.

Preferably m is an integer in the range of ≧1 to ≦25 and m′ is an integer in the range of ≧1 to ≦25, more preferably m is an integer in the range of ≧1 to ≦20 and m′ is an integer in the range of ≧1 to ≦20.

Preferably (m+m′) is an integer in the range of ≧3 to ≦65, more preferably (m+m′) is an integer in the range of ≧3 to ≦50, even more preferably (m+m′) is an integer in the range of ≧3 to ≦40.

Preferably the ratio of (m+m′) to k is in the range of 0.3:1 to 6:1, more preferably in the range of 0.3:1 to 5:1, most preferably in the range of 0.3:1 to 4:1, even more preferably in the range of 0.3:1 to 3:1.

Preferably n is an integer in the range of ≧6 to ≦40 and n′ is an integer in the range of ≧6 to ≦40, more preferably n is an integer in the range of ≧8 to ≦35 and p′ is an integer in the range of ≧8 to ≦35.

Preferably (n+n′) is an integer in the range of ≧10 to ≦80, more preferably (n+n′) is an integer in the range of ≧15 to ≦70.

Preferably p is an integer in the range of ≧5 to ≦25 and p′ is an integer in the range of ≧5 to ≦25, more preferably p is an integer in the range of ≧5 to ≦15 and p′ is an integer in the range of ≦5 to ≦15.

Preferably (p+p′) is an integer in the range of ≧10 to ≦30, more preferably (p+p′) is an integer in the range of ≧15 to ≦30.

Preferably R1 denotes an unsubstituted, linear alkyl radical having 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 or 18 carbon atoms. More preferably R1 denotes an unsubstituted, linear alkyl radical having 8, 9, 10, 11, 12, 13, 14, 15 or 16 carbon atoms. Most preferably R1 denotes an unsubstituted, linear alkyl radical having 8, 9, 10, 11 or 12 carbon atoms.

In case the alkoxylated polytetrahydrofuran comprises units, wherein R2 denotes —CH2-CH3, the ratio of (n+n′) to k is in the range of 1.5:1 to 10:1, more preferably in the range of 1.5:1 to 6:1, most preferably in the range of 2:1 to 5:1.

In case the alkoxylated polytetrahydrofuran comprises units, wherein R3 denotes —CH3, the ratio of (p+p′) to k is in the range of 1.2:1 to 10:1, more preferably in the range of 1.2:1 to 6:1.

In another preferred embodiment the presently claimed invention is directed to the use of an alkoxylated polytetrahydrofuran of general formula (II)

Wherein:

m is an integer in the range of ≧1 to ≦30,

m′ is an integer in the range of ≧1 to ≦30,

(m+m′) is an integer in the range of ≧3 to ≦50,

n is an integer in the range of ≧3 to ≦45,

n′ is an integer in the range of ≧3 to ≦45,

(n+n′) is an integer in the range of ≧6 to ≦90,

p is an integer in the range of ≧0 to ≦75,

p′ is an integer in the range of ≧0 to ≦75,

k is an integer in the range of ≧3 to ≦25,

(p+p′) is an integer in the range of ≧0 to ≦30,

k is an integer in the range of ≧3 to ≦25,

R1 denotes an unsubstituted, linear alkyl radical having 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 or 18 carbon atoms,

R2 denotes —CH2-CH3, and

R3 denotes —CH3,

whereby the concatenations denoted by k are distributed to form a block polymeric structure and the concatenations denoted by p, p′, n, n′, m and m′ are distributed to form a block polymeric structure or a random polymeric structure, as a lubricant.

In a more preferred embodiment the presently claimed invention is directed to the use of an alkoxylated polytetrahydrofuran of general formula (II)

Wherein:

m is an integer in the range of ≧1 to ≦30,

m′ is an integer in the range of ≧1 to ≦30,

(m+m′) is an integer in the range of ≧3 to ≦50,

n is an integer in the range of ≧3 to ≦45,

n′ is an integer in the range of ≧3 to ≦45,

(n+n′) is an integer in the range of ≧6 to ≦90,

p is an integer in the range of 0 to ≦75,

p′ is an integer in the range of ≧0 to ≦75,

k is an integer in the range of ≧3 to ≦25,

(p+p′) is an integer in the range of ≧0 to ≦30,

k is an integer in the range of ≧3 to ≦25,

R1 denotes an unsubstituted, linear alkyl radical having 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 or 18 carbon atoms,

R2 denotes —CH2-CH3, and

R3 denotes —CH3,

whereby the concatenations denoted by k are distributed to form a block polymeric structure and the concatenations denoted by p, p′, n, n′, m and m′ are distributed to form a block polymeric structure or a random polymeric structure, wherein the ratio of (m+m′) to k is in the range of 0.3:1 to 6:1 and the ratio of (n+n′) to k is in the range of 1.5:1 to 10:1, as a lubricant.

In a most preferred embodiment the presently claimed invention is directed to the use of an alkoxylated polytetrahydrofuran of general formula (II)

Wherein:

m is an integer in the range of ≧1 to ≦25,

m′ is an integer in the range of ≧1 to ≦25,

(m+m′) is an integer in the range of ≧3 to ≦40,

n is an integer in the range of ≧6 to ≦40,

n′ is an integer in the range of ≧6 to ≦40,

(n+n′) is an integer in the range of ≧12 to ≦70,

p is an integer in the range of ≧0 to ≦25,

p′ is an integer in the range of ≧0 to ≦25,

(p+p′) is an integer in the range of ≧0 to ≦30,

k is an integer in the range of ≧5 to ≦20,

R1 denotes an unsubstituted, linear alkyl radical having 8, 9, 10, 11 or 12 carbon atoms,

R2 denotes —CH2-CH3, and

R3 denotes —CH3,

whereby the concatenations denoted by k are distributed to form a block polymeric structure and the concatenations denoted by p, p′, n, n′, m and m′ are distributed to form a block polymeric structure or a random polymeric structure,

wherein the ratio of (m+m′) to k is in the range of 0.3:1 to 4:1 and the ratio of (n+n′) to k is in the range of 1.5:1 to 5:1, as a lubricant.

In another preferred embodiment the presently claimed invention is directed to the use of an alkoxylated polytetrahydrofuran of general formula (II)

Wherein:

m is an integer in the range of ≧1 to ≦25,

m′ is an integer in the range of ≧1 to ≦25,

(m+m′) is an integer in the range of ≧3 to ≦50,

n is an integer in the range of ≧0 to ≦45,

n′ is an integer in the range of ≧0 to ≦45,

(n+n′) is an integer in the range of ≧0 to ≦80,

p is an integer in the range of ≧3 to ≦45,

p′ is an integer in the range of ≧3 to ≦45,

(p+p′) is an integer in the range of ≧6 to ≦90,

k is an integer in the range of ≧3 to ≦25,

R1 denotes an unsubstituted, linear alkyl radical having 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 or 18 carbon atoms,

R2 denotes —CH2-CH3,

and

R3 denotes —CH3,

whereby the concatenations denoted by k are distributed to form a block polymeric structure and the concatenations denoted by p, p′, n, n′, m and m′ are distributed to form a block polymeric structure or a random polymeric structure, as a lubricant.

In a more preferred embodiment the presently claimed invention is directed to the use of an alkoxylated polytetrahydrofuran of general formula (II)

Wherein:

m is an integer in the range of ≧1 to ≦30,

m′ is an integer in the range of ≧1 to ≦30,

(m+m′) is an integer in the range of ≧3 to ≦50,

n is an integer in the range of ≧0 to ≦45,

n′ is an integer in the range of ≧0 to ≦45,

(n+n′) is an integer in the range of ≧0 to ≦80,

p is an integer in the range of ≧3 to 45,

p′ is an integer in the range of ≧3 to ≦45,

(p+p′) is an integer in the range of ≧6 to ≦90,

k is an integer in the range of ≧3 to ≦25,

R1 denotes an unsubstituted, linear alkyl radical having 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 or 18 carbon atoms,

R2 denotes —CH2-CH3, and

R3 denotes —CH3,

whereby the concatenations denoted by k are distributed to form a block polymeric structure and the concatenations denoted by p, p′, n, n′, m and m′ are distributed to form a block polymeric structure or a random polymeric structure, wherein the ratio of (m+m′) to k is in the range of 0.3:1 to 6:1 and the ratio of (p+p′) to k is in the range of 1.5:1 to 10:1, as a lubricant.

In a most preferred embodiment the presently claimed invention is directed to the use of an alkoxylated polytetrahydrofuran of general formula (II)

Wherein:

m is an integer in the range of ≧1 to ≦25,

m′ is an integer in the range of ≧1 to ≦25,

(m+m′) is an integer in the range of ≧3 to ≦50,

n is an integer in the range of ≧0 to ≦45,

n′ is an integer in the range of ≧0 to ≦45,

(n+n′) is an integer in the range of ≧0 to ≦80,

p is an integer in the range of ≧5 to ≦20,

p′ is an integer in the range of ≧5 to ≦20,

(p+p′) is an integer in the range of ≧10 to ≦30,

k is an integer in the range of ≧5 to ≦20,

R1 denotes an unsubstituted, linear alkyl radical having 8, 9, 10, 11 or 12 carbon atoms,

R2 denotes —CH2-CH3, and

R3 denotes —CH3,

whereby the concatenations denoted by k are distributed to form a block polymeric structure and the concatenations denoted by p, p′, n, n′, m and m′ are distributed to form a block polymeric structure or a random polymeric structure, wherein the ratio of (m+m′) to k is in the range of 0.3:1 to 4:1 and the ratio of (p+p′) to k is in the range of 1.5:1 to 5:1, as a lubricant.

The alkoxylated polytetrahydrofurans are obtained by reacting at least one polytetrahydrofuran block polymer with at least one C8-C3 epoxy alkane and optionally at least one epoxide selected from the group consisting of ethylene oxide, propylene oxide and butylene oxide in the presence of at least one catalyst. In case at least one epoxide selected from the group consisting of ethylene oxide, propylene oxide and butylene oxide is used, the at least one C8-C30 epoxy alkane and the at least one epoxide selected from the group consisting of ethylene oxide, propylene oxide and butylene oxide can either be added as a mixture of epoxides to obtain a random copolymer or in portions, whereby each portion contains a different epoxide, to obtain a block copolymer.

Preferably the at least one C8-C30 epoxy alkane is selected from the group consisting of 1,2-epoxyoctane; 1,2-epoxynonane; 1,2-epoxydecane; 1,2-epoxyundecane; 1,2-epoxydodecane; 1,2-epoxytridecane; 1,2-epoxytetradecane; 1,2-epoxypentadecane; 1,2-epoxyhexadecane; 1,2-epoxyheptadecane; 1,2-epoxyoctadecane; 1,2-epoxynonadecane; 1,2-epoxylcosane; 1,2-epoxyunicosane; 1,2-epoxydocosane; 1,2-epoxytricosane; 1,2-epoxytetracosane; 1,2-epoxypentacosane; 1,2-epoxyhexacosane; 1,2-epoxyheptacosane; 1,2-epoxyoctacosane; 1,2-epoxynonacosane and 1,2-epoxytriacontane.

Preferably the at least one catalyst is a base or a double metal cyanide catalyst (DMC catalyst). More preferably the at least one catalyst is selected from the group consisting of alkaline earth metal hydroxides such as calcium hydroxide, strontium hydroxide and barium hydroxide, alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide and caesium hydroxide and alkali metal alkoxylates such as potassium tert-butoxylate. Most preferably the at least one catalyst is sodium hydroxide or potassium tert-butoxylate. Most preferably the at least one catalyst is potassium tert-butoxylate.

In case the catalyst is a base, any inert solvents capable of dissolving alkoxylated polytetrahydrofuran and polytetrahydrofuran may be used as solvents during the reaction or as solvents required for working up the reaction mixture in cases where the reaction is carried out without solvents. The following solvents are mentioned as examples: methylene chloride, trichloroethylene, tetrahydrofuran, dioxane, methyl ethyl ketone, methylisobutyl ketone, ethyl acetate and isobutyl acetate.

In case the catalyst is a base, the amount of catalysts used is preferably in the range from 0.01 to 1.0, more preferably in the range from 0.05 to 0.5, % by weight, based on the total amount of the alkoxylated polytetrahydrofuran. The reaction is preferably carried out at a temperature in the range of 70 to 200° C., more preferably from 100 to 160° C. The pressure is preferably in the range from 1 bar to 150 bar, more preferably in the range from 3 to 30 bar.

In case a DMC catalyst is used, it is in principle possible to use all types of DMC catalysts known from the prior art. Preference is given to using double metal cyanide catalysts of the general formula (1):

M1_(a)[M²(CN)_(b)(A)_(c)]_(d) fM¹ gX_(n) h(H2O).eL,  (1)

Wherein:

M1 is a metal ion selected from the group comprising Zn2+, Fe2+, Co3+, Ni2+, Mn2+, Co2+, Sn2+, Pb2+, Mo4+, Mo6+, Al3+, V4+, V5+, Sr2+, W6+, Cr2+, Cr3+ and Cd2+,

M2 is a metal ion selected from the group comprising Fe2+, Fe3+, Co2+, Co3+, Mn2+, Mn3+, V4+, V5+, Cr2+, C3+, Rh3+, Ru2+ and Ir3+,

M1 and M2 are identical or different,

A is an anion selected from the group comprising halide, hydroxide, sulfate, carbonate, cyanide, thiocyanate, isocyanate, cyanate, carboxylate, oxalate and nitrate, X is an anion selected from the group comprising halide, hydroxide, sulfate, carbonate, cyanide, thiocyanate, Isocyanate, cyanate, carboxylate, oxalate and nitrate,

L is a water-miscible ligand selected from the group comprising alcohols, aldehydes, ketones, ethers, polyethers, esters, ureas, amides, nitriles and sulfides, and

a, b, c, d, g and n are selected so that the compound is electrically neutral, and

e is the coordination number of the ligand or zero,

f is a fraction or integer greater than or equal to zero,

h is a fraction or integer greater than or equal to zero.

Such compounds are generally known and can be prepared, for example, by the process described in EP 0 862 947 B1 by combining the aqueous solution of a water-soluble metal salt with the aqueous solution of a hexacyanometallate compound, in particular of a salt or an acid, and, if necessary, adding a water-soluble ligand thereto either during or after the combination of the two solutions.

DMC catalysts are usually prepared as a solid and used as such. The catalyst is typically used as powder or in suspension. However, other ways known to those skilled in the art for using catalysts can likewise be employed. In a preferred embodiment, the DMC catalyst is dispersed with an Inert or non-inert suspension medium which can be, for example, the product to be produced or an intermediate by suitable measures, e.g. milling. The suspension produced in this way is used, if appropriate after removal of interfering amounts of water by methods known to those skilled in the art, e.g. stripping with or without use of inert gases such as nitrogen and/or noble gases. Suitable suspension media are, for example, toluene, xylene, tetrahydrofuran, acetone, 2-methylpentanone, cyclohexanone and also polyether alcohols according to the invention and mixtures thereof. The catalyst is preferably used in a suspension in a polyol as described, for example, in EP 0 090 444 A, which is incorporated by reference in its entirety.

In another embodiment, the presently claimed invention is directed to the use of at least one alkoxylated polytetrahydrofuran as defined above or a mixture of polytetrahydrofurans as defined above for the preparation of a lubricating oil composition.

In another embodiment, the presently claimed invention is directed to a lubricating oil composition comprising at least one alkoxylated polytetrahydrofuran as defined above or a mixture of alkoxylated polytetrahydrofuran as defined above. Preferably the lubricating oil composition comprises ≧1% to ≦10% by weight or ≧1% to ≦40% by weight or ≧20% to ≦100% by weight, more preferably ≧1% to ≦5% by weight or ≧1% to ≦35% by weight or ≧25% to ≦100% by weight, most preferably ≧1% to ≦2% by weight or ≧2% to ≦30% by weight or ≧30% to ≦100% by weight, of at least one alkoxylated polytetrahydrofuran as defined above, related to the total amount of the lubricating oil composition.

Preferably, the lubricating oil composition according to the presently claimed invention has a friction coefficient in the range of 0.003 to 0.030 at 25% slide roll ratio (SRR) determined using mini-traction machine (MTM) measurements at 70° C. and 1 GPa.

In another embodiment, the presently claimed invention relates to an industrial oil comprising at least one alkoxylated polytetrahydrofuran.

Lubricating oil compositions comprising at least one alkoxylated polytetrahydrofuran as defined above or a mixture of polytetrahydrofurans as defined above can be used for various applications such as light, medium and heavy duty engine oils, industrial engine oils, marine engine oils, automotive engine oils, crankshaft oils, compressor oils, refrigerator oils, hydrocarbon compressor oils, very low-temperature lubricating oils and fats, high temperature lubricating oils and fats, wire rope lubricants, textile machine oils, refrigerator oils, aviation and aerospace lubricants, aviation turbine oils, transmission oils, gas turbine oils, spindle oils, spin oils, traction fluids, transmission oils, plastic transmission oils, passenger car transmission oils, truck transmission oils, industrial transmission oils, industrial gear oils, insulating oils, instrument oils, brake fluids, transmission liquids, axle lubricating oils, shock absorber oils, heat distribution medium oils, transformer oils, fats, chain oils, minimum quantity lubricants for metalworking operations, oil to the warm and cold working, oil for water-based metalworking liquids, oil for neat oil metalworking fluids, oil for semi-synthetic metalworking fluids, oil for synthetic metalworking fluids, drilling detergents for the soil exploration, hydraulic oils, in biodegradable lubricants or lubricating greases or waxes, chain saw oils, release agents, moulding fluids, gun, pistol and rifle lubricants or watch lubricants and food grade approved lubricants.

A lubricating oil composition can comprise of base stocks, co-solvents and a variety of different additives in varying ratios.

Preferably the lubricating oil composition further comprises base stocks selected from the group consisting of mineral oils (Group I, II or III oils), polyalphaolefins (Group IV oils), polymerized and interpolymerized olefins, alkyl naphthalenes, alkylene oxide polymers, silicone oils, phosphate esters and carboxylic acid esters (Group V oils). Preferably the lubricating oil comprises ≧50% to ≦99% by weight or ≧80% to ≦99% by weight or ≧90% to ≦99% by weight base stocks, related to the total amount of the lubricating oil composition.

Definitions for the base stocks in this invention are the same as those found in the American Petroleum Institute (API) publication “Engine Oil Licensing and Certification System”, Industry Services Department, Fourteenth Edition, December 1996, Addendum 1, December 1998. Said publication categorizes base stocks as follows:

a) Group I base stocks contain less than 90 percent saturates and/or greater than 0.03 percent sulphur and have a viscosity Index greater than or equal to 80 and less than 120 using the test methods specified in the following table

b) Group II base stocks contain greater than or equal to 90 percent saturates and less than or equal to 0.03 percent sulphur and have a viscosity index greater than or equal to 80 and less than 120 using the test methods specified in the following table

c) Group III base stocks contain greater than or equal to 90 percent saturates and less than or equal to 0.03 percent sulphur and have a viscosity index greater than or equal to 120 using the test methods specified in the following table

Analytical Methods for Base Stock

Property Test Method Saturates ASTM D 2007 Viscosity Index ASTM D 2270 Sulphur ASTM D 2622 ASTM D 4294 ASTM D 4927 ASTM D 3120

Group IV base stocks contain polyalphaolefins. Synthetic lower viscosity fluids suitable for the present invention include the polyalphaolefins (PAOs) and the synthetic oils from the hydrocracking or hydroisomerization of Fischer Tropsch high boiling fractions, including waxes. These are both stocks comprised of saturates with low impurity levels consistent with their synthetic origin. The hydroisomerized Fischer Tropsch waxes are highly suitable base stocks, comprising saturated components of iso-paraffinic character (resulting from the isomerization of the predominantly n-paraffins of the Fischer Tropsch waxes) which give a good blend of high viscosity Index and low pour point. Processes for the hydrosomerization of Fischer Tropsch waxes are described in U.S. Pat. Nos. 5,362,378; 5,565,086; 5,246,566 and 5,135,638, as well in EP 710710, EP 321302 and EP 321304.

Polyalphaolefins suitable for the present invention, as either lower viscosity or high viscosity fluids depending on their specific properties, include known PAO materials which typically comprise relatively low molecular weight hydrogenated polymers or oligomers of alphaolefins which include but are not limited to C₂ to about C₃₂ alphaolefins with the C₈ to about C₁₆ alphaolefins, such as 1-octene, 1-decene, 1-dodecene and the like being preferred. The preferred polyalphaolefins are poly-1-octene, poly-1-decene, and poly-1-dodecene, although the dimers of higher olefins in the range of C₁₄ to C₁₈ provide low viscosity base stocks.

Low viscosity PAO fluids suitable for the present invention, may be conveniently made by the polymerization of an alphaolefin in the presence of a polymerization catalyst such as the Friedel-Crafts catalysts Including, for example, aluminum trichloride, boron trifluoride or complexes of boron trifluoride with water, alcohols such as ethanol, propanol or butanol, carboxylic acids or esters such as ethyl acetate or ethyl propionate. For example, the methods disclosed by U.S. Pat. Nos. 4,149,178 or 3,382,291 may be conveniently used herein. Other descriptions of PAO synthesis are found in the following U.S. Pat. No. 3,742,082 (Brennan); U.S. Pat. No. 3,769,363 (Brennan); U.S. Pat. No. 3,876,720 (Heilman); U.S. Pat. No. 4,239,930 (Allphin); U.S. Pat. No. 4,367,352 (Watts); U.S. Pat. No. 4,413,156 (Watts); U.S. Pat. No. 4,434,408 (Larkin); U.S. Pat. No. 4,910,355 (Shubkin); U.S. Pat. No. 4,956,122 (Watts); and U.S. Pat. No. 5,068,487 (Theriot).

Group V base stocks contain any base stocks not described by Groups I to IV. Examples of Group V base stocks include alkyl naphthalenes, alkylene oxide polymers, silicone oils, phosphate esters and carboxylic acid esters.

Synthetic lubricating oils include hydrocarbon oils and halo-substituted hydrocarbon oils such as polymerized and interpolymerized olefins (e.g., polybutylenes, polypropylenes, propylene-isobutylene copolymers, chlorinated polybutylenes, poly(1-hexenes), poly(1-octenes), poly(1-decenes)); alkylbenzenes (e.g., dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes, di(2-ethylhexyl)benzenes); polyphenyls (e.g., biphenyls, terphenyls, alkylated polyphenols); and alkylated diphenyl ethers and alkylated diphenyl sulphides and derivative, analogs and homologs thereof.

Further carboxylic acid esters suitable for the present invention include the esters of mono and polybasic acids with monoalkanols (simple esters) or with mixtures of mono and polyalkanols (complex esters), and the polyol esters of monocarboxylic acids (simple esters), or mixtures of mono and polycarboxylic acids (complex esters). Esters of the mono/polybasic type include, for example, the esters of monocarboxylic acids such as heptanoic acid, and dicarboxylic acids such as phthalic acid, succinic acid, alkyl succinic acid, alkenyl succinic acid, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic acid dimer, malonic acid, alkyl malonic acid, alkenyl malonic acid, etc., with a variety of alcohols such as butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, or mixtures thereof with polyalkanols, etc. Specific examples of these types of esters include nonyl heptanoate, dibutyl adipate, di(2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, dibutyl-TMP-adipate, etc.

Also suitable for the present invention are esters, such as those obtained by reacting one or more polyhydric alcohols, preferably the hindered polyols such as the neopentyl polyols, e.g. neopentyl glycol, trimethylol ethane, 2-methyl-2-propyl-1,3-propanediol, trimethylol propane, trimethylol butane, pentaerythritol and dipentaerythritol with monocarboxylic acids containing at least 4 carbons, normally the C5 to C30 acids such as saturated straight chain fatty acids including caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachic acid, and behenic acid, or the corresponding branched chain fatty acids or unsaturated fatty acids such as oleic acid, or mixtures thereof, with polycarboxylic acids.

Alkylene oxide polymers and interpolymers and derivatives thereof where the terminal hydroxyl groups have been modified by esterification, etherification, etc., constitute another class of known synthetic lubricating oils. These are exemplified by polyoxyalkylene polymers prepared by polymerization of ethylene oxide or propylene oxide, and the alkyl and aryl ethers of polyoxyalkylene polymers (e.g., methyl-polyiso-propylene glycol ether having a molecular weight of 1000 or diphenyl ether of poly-ethylene glycol having a molecular weight of 1000 to 1500); and mono- and polycarboxylic esters thereof, for example, the acetic acid esters, mixed C3-C8 fatty acid esters and C13 Oxo acid diester of tetraethylene glycol.

Silicon-based oils such as the polyalkyl-, polyaryl-, polyalkoxy- or polyaryloxysilicone oils and silicate oils comprise another useful class of synthetic lubricants; such oils include tetraethyl silicate, tetraisopropyl silicate, tetra-(2-ethylhexyl)silicate, tetra-(4-methyl-2-ethylhexyl)silicate, tetra-(p-tert-butyl-phenyl) silicate, hexa-(4-methyl-2-ethylhexyl)disiloxane, oly(methyl)siloxanes and poly(methylphenyl)siloxanes. Other synthetic lubricating oils include liquid esters of phosphorous-containing acids (e.g., tricresyl phosphate, trioctyl phosphate, diethyl ester of decylphosphonic acid) and polymeric tetrahydrofurans.

The lubricating oil composition of the invention optionally further includes at least one other performance additive. The other performance additives include dispersants, metal deactivators, detergents, viscosity modifiers, extreme pressure agents (typically boron- and/or sulphur- and/or phosphorus-containing), antiwear agents, antioxidants (such as hindered phenols, aminic antioxidants or molybdenum compounds), corrosion inhibitors, foam inhibitors, demulsifiers, pour point depressants, seal swelling agents, friction modifiers and mixtures thereof.

The total combined amount of the other performance additives (excluding the viscosity modifiers) present on an oil free basis may Include ranges of 0% by weight to 25% by weight, or 0.01% by weight to 20% by weight, or 0.1% by weight to 15% by weight or 0.5% by weight to 10% by weight, or 1 to 5% by weight of the composition.

Although one or more of the other performance additives may be present, it is common for the other performance additives to be present in different amounts relative to each other.

In one embodiment the lubricating composition further includes one or more viscosity modifiers.

When present the viscosity modifier may be present in an amount of 0.5% by weight to 70% by weight, 1% by weight to 60% by weight, or 5% by weight to 50% by weight, or 10% by weight to 50% by weight of the lubricating composition.

Viscosity modifiers include (a) polymethacrylates, (b) esterified copolymers of (II) a vinyl aromatic monomer and (ii) an unsaturated carboxylic acid, anhydride, or derivatives thereof, (c) esterified interpolymers of (II) an alpha-olefin; and (ii) an unsaturated carboxylic acid, anhydride, or derivatives thereof, or (d) hydrogenated copolymers of styrene-butadiene, (e) ethylene-propylene copolymers, (f) polyisobutenes, (g) hydrogenated styrene-isoprene polymers, (h) hydrogenated isoprene polymers, or (II) mixtures thereof.

In one embodiment the viscosity modifier includes (a) a polymethacrylate, (b) an esterified copolymer of (II) a vinyl aromatic monomer, and (i) an unsaturated carboxylic acid, anhydride, or derivatives thereof, (c) an esterified interpolymer of (II) an alpha-olefin; and (ii) an unsaturated carboxylic acid, anhydride, or derivatives thereof, or (d) mixtures thereof.

Extreme pressure agents include compounds containing boron and/or sulphur and/or phosphorus.

The extreme pressure agent may be present in the lubricating composition at 0% by weight to 20% by weight, or 0.05% by weight to 10% by weight, or 0.1% by weight to 8% by weight of the lubricating composition.

In one embodiment the extreme pressure agent is a sulphur-containing compound. In one embodiment the sulphur-containing compound may be a sulphurised olefin, a polysulphide, or mixtures thereof. Examples of the sulphurised olefin include a sulphurised olefin derived from propylene, isobutylene, pentene; an organic sulphide and/or polysulphide including benzyldisulphide; bis-(chlorobenzyl) disulphide; dibutyl tetrasulphide; di-tertiary butyl polysulphide; and sulphurised methyl ester of oleic acid, a sulphurised alkylphenol, a sulphurised dipentene, a sulphurised terpene, a sulphurised Diels-Alder adduct, an alkyl sulphenyl N′N-dialkyl dithiocarbamates; or mixtures thereof.

In one embodiment the sulphurised olefin includes a sulphurised olefin derived from propylene, isobutylene, pentene or mixtures thereof.

In one embodiment the extreme pressure agent sulphur-containing compound includes a dimercaptothiadiazole or derivative, or mixtures thereof. Examples of the dimercaptothiadiazole include compounds such as 2,5-dimercapto-1,3,4-thiadiazole or a hydrocarbyl-substituted 2,5-dimercapto-1,3,4-thiadiazole, or oligomers thereof. The oligomers of hydrocarbyl-substituted 2,5-dimercapto-1,3,4-thiadiazole typically form by forming a sulphur-sulphur bond between 2,5-dimercapto-1,3,4-thiadiazole units to form derivatives or oligomers of two or more of said thiadiazole units. Suitable 2,5-dimercapto-1,3,4-thiadiazole derived compounds include for example 2,5-bis(tert-nonyldithio)-1,3,4-thiadiazole or 2-tert-nonyldithio-5-mercapto-1,3,4-thiadiazole. The number of carbon atoms on the hydrocarbyl substituents of the hydrocarbyl-substituted 2,5-dimercapto-1,3,4-thiadiazole typically Include 1 to 30, or 2 to 20, or 3 to 16.

In one embodiment the dimercaptothiadiazole may be a thiadiazole-functionalised dispersant. A detailed description of the thiadiazole-functionalised dispersant is described is paragraphs [0028] to [0052] of International Publication WO 2008/014315. The subject matter of paragraphs [0028] to [0052] are incorporated by reference in their entirety.

The thiadiazole-functionalised dispersant may be prepared by a method including heating, reacting or complexing a thiadiazole compound with a dispersant substrate. The thiadiazole compound may be covalently bonded, salted, complexed or otherwise solubilised with a dispersant, or mixtures thereof.

The relative amounts of the dispersant substrate and the thiadiazole used to prepare the thiadiazole-functionalised dispersant may vary. In one embodiment the thiadiazole compound is present at 0.1 to 10 parts by weight relative to 100 parts by weight of the dispersant substrate. In different embodiments the thiadiazole compound is present at greater than 0.1 to 9, or greater than 0.1 to less than 5, or 0.2 to less than 5: to 100 parts by weight of the dispersant substrate. The relative amounts of the thiadiazole compound to the dispersant substrate may also be expressed as (0.1-10):100, or (>0.1-9):100, (such as (>0.5-9):100), or (0.1 to less than 5): 100, or (0.2 to less than 5): 100.

In one embodiment the dispersant substrate is present at 0.1 to 10 parts by weight relative to 1 part by weight of the thiadiazole compound. In different embodiments the dispersant substrate is present at greater than 0.1 to 9, or greater than 0.1 to less than 5, or about 0.2 to less than 5: to 1 part by weight of the thiadiazole compound. The relative amounts of the dispersant substrate to the thiadiazole compound may also be expressed as (0.1-10):1, or (>0.1-9):1, (such as (>0.5-9):1), or (0.1 to less than 5): 1, or (0.2 to less than 5): 1.

The thiadiazole-functionalised dispersant may be derived from a substrate that includes a succinimide dispersant (for example, N-substituted long chain alkenyl succinimides, typically a polyisobutylene succinimide), a Mannich dispersant, an ester-containing dispersant, a condensation product of a fatty hydrocarbyl monocarboxylic acylating agent with an amine or ammonia, an alkyl amino phenol dispersant, a hydrocarbyl-amine dispersant, a polyether dispersant, a polyetheramine dispersant, a viscosity modifier containing dispersant functionality (for example polymeric viscosity index modifiers (VMs) containing dispersant functionality), or mixtures thereof. In one embodiment the dispersant substrate includes a succinimide dispersant, an ester-containing dispersant or a Mannich dispersant.

In one embodiment the extreme pressure agent includes a boron-containing compound. The boron-containing compound includes a borate ester (which in some embodiments may also be referred to as a borated epoxide), a borated alcohol, a borated dispersant, a borated phospholipid or mixtures thereof. In one embodiment the boron-containing compound may be a borate ester or a borated alcohol.

The borate ester may be prepared by the reaction of a boron compound and at least one compound selected from epoxy compounds, halohydrin compounds, epihalohydrin compounds, alcohols and mixtures thereof. The alcohols include dihydric alcohols, trihydric alcohols or higher alcohols, with the proviso for one embodiment that hydroxyl groups are on adjacent carbon atoms, i.e., vicinal.

Boron compounds suitable for preparing the borate ester include the various forms selected from the group consisting of boric acid (including metaboric acid, orthoboric acid and tetraboric acid), boric oxide, boron trioxide and alkyl borates. The borate ester may also be prepared from boron halides.

In one embodiment suitable borate ester compounds include tripropyl borate, tributyl borate, tripentyl borate, trihexyl borate, triheptyl borate, trioctyl borate, trinonyl borate and tridecyl borate. In one embodiment the borate ester compounds include tributyl borate, tri-2-ethylhexyl borate or mixtures thereof.

In one embodiment, the boron-containing compound is a borated dispersant, typically derived from an N-substituted long chain alkenyl succinimide. In one embodiment the borated dispersant includes a polyisobutylene succinimide. Borated dispersants are described in more detail in U.S. Pat. No. 3,087,936; and U.S. Pat. No. 3,254,025, which are incorporated by reference in their entirety.

In one embodiment the borated dispersant may be used m combination with a sulphur-containing compound or a borate ester.

In one embodiment the extreme pressure agent is other than a borated dispersant.

The number average molecular weight of the hydrocarbon from which the long chain alkenyl group was derived includes ranges of 350 to 5000, or 500 to 3000, or 550 to 1500. The long chain alkenyl group may have a number average molecular weight of 550, or 750, or 950 to 1000.

The N-substituted long chain alkenyl succinimides are borated using a variety of agents Including boric acid (for example, metaboric acid, orthoboric acid and tetraboric acid), boric oxide, boron trioxide, and alkyl borates. In one embodiment the borating agent is boric acid which may be used alone or in combination with other borating agents.

The borated dispersant may be prepared by blending the boron compound and the N-substituted long chain alkenyl succinimides and heating them at a suitable temperature, such as, 80° C. to 250° C., or 90° C. to 230° C., or 100° C. to 210° C., until the desired reaction has occurred. The molar ratio of the boron compounds to the N-substituted long chain alkenyl succinimides may have ranges including 10:1 to 1:4, or 4:1 to 1:3; or the molar ratio of the boron compounds to the N-substituted long chain alkenyl succinimides may be 1:2. Alternatively, the ratio of moles B:moles N (that is, atoms of B:atoms of N) in the borated dispersant may be 0.25:1 to 10:1 or 0.33:1 to 4:1 or 0.2:1 to 1.5:1, or 0.25:1 to 1.3:1 or 0.8:1 to 1.2:1 or about 0.5:1 An inert liquid may be used in performing the reaction. The liquid may include toluene, xylene, chlorobenzene, dimethylformamide or mixtures thereof.

In one embodiment the lubricating composition further includes a borated phospholipid. The borated phospholipid may be derived from boronation of a phospholipid (for example boronation may be carried out with boric acid). Phospholipids and lecithins are described in detail in Encyclopedia of Chemical Technology, Kirk and Othmer, 3rd Edition, in “Fats and Fatty Oils”, Volume 9, pages 795-831 and in “Lecithins”, Volume 14, pages 250-269, which is incorporated by reference in its entirety.

The phospholipid may be any lipid containing a phosphoric acid, such as lecithin or cephalin, or derivatives thereof. Examples of phospholipids include phosphatidylcholine, phosphatidylserine, phosphatidylinositol, phosphatidylethanolamine, phosphotidic acid and mixtures thereof. The phospholipids may be glycerophospholipids, glycerol derivatives of the above list of phospholipids. Typically, the glycerophospholipids have one or two acyl, alkyl or alkenyl groups on a glycerol residue. The alkyl or alkenyl groups may contain 8 to 30, or 8 to 25, or 12 to 24 carbon atoms. Examples of suitable alkyl or alkenyl groups include octyl, dodecyl, hexadecyl, octadecyl, docosanyl, octenyl, dodecenyl, hexadecenyl and octadecenyl.

Phospholipids may be prepared synthetically or derived from natural sources. Synthetic phospholipids may be prepared by methods known to those in the art. Naturally derived phospholipids are often extracted by procedures known to those in the art. Phospholipids may be derived from animal or vegetable sources. A useful phospholipid is derived from sunflower seeds. The phospholipid typically contains 35% to 60% phosphatidylcholine, 20% to 35% phosphatidylinositol, 1% to 25% phosphatidic acid, and 10% to 25% phosphatidylethanolamine, wherein the percentages are by weight based on the total phospholipids. The fatty acid content may be 20% by weight to 30% by weight palmitic acid, 2% by weight to 10% by weight stearic acid, 15% by weight to 25% by weight oleic acid, and 40% by weight to 55% by weight linoleic acid.

Friction modifiers may include fatty amines, esters such as borated glycerol esters, fatty phosphites, fatty acid amides, fatty epoxides, borated fatty epoxides, alkoxylated fatty amines, borated alkoxylated fatty amines, metal salts of fatty acids, or fatty imidazolines, condensation products of carboxylic acids and polyalkylene-polyamines.

In one embodiment the lubricating composition may contain phosphorus- or sulphur-containing antiwear agents other than compounds described as an extreme pressure agent of the amine salt of a phosphoric acid ester described above. Examples of the antiwear agent may include a non-ionic phosphorus compound (typically compounds having phosphorus atoms with an oxidation state of +3 or +5), a metal dialkyldithiophosphate (typically zinc dialkyldithiophosphates), a metal mono- or di-alkylphosphate (typically zinc phosphates), or mixtures thereof.

The non-ionic phosphorus compound includes a phosphite ester, a phosphate ester, or mixtures thereof.

In one embodiment the lubricating composition of the invention further includes a dispersant. The dispersant may be a succinimide dispersant (for example N-substituted long chain alkenyl succinimides), a Mannich dispersant, an ester-containing dispersant, a condensation product of a fatty hydrocarbyl monocarboxylic acylating agent with an amine or ammonia, an alkyl amino phenol dispersant, a hydrocarbyl-amine dispersant, a polyether dispersant or a polyetheramine dispersant.

In one embodiment the succinimide dispersant includes a polyisobutylene-substituted succinimide, wherein the polyisobutylene from which the dispersant is derived may have a number average molecular weight of 400 to 5000, or 950 to 1600.

Succinimide dispersants and their methods of preparation are more fully described in U.S. Pat. Nos. 4,234,435 and 3,172,892, which are incorporated by reference in their entirety.

Suitable ester-containing dispersants are typically high molecular weight esters. These materials are described in more detail in U.S. Pat. No. 3,381,022, which is incorporated by reference in its entirety.

In one embodiment the dispersant includes a borated dispersant. Typically the borated dispersant includes a succinimide dispersant including a polyisobutylene succinimide, wherein the polyisobutylene from which the dispersant is derived may have a number average molecular weight of 400 to 5000. Borated dispersants are described in more detail above within the extreme pressure agent description.

Dispersant viscosity modifiers (often referred to as DVMs) include functionalised polyolefins, for example, ethylene-propylene copolymers that have been functionalized with the reaction product of maleic anhydride and an amine, a polymethacrylate functionalized with an amine, or esterified styrene-maleic anhydride copolymers reacted with an amine may also be used in the composition of the invention.

Corrosion inhibitors include 1-amino-2-propanol, octylamine octanoate, condensation products of dodecenyl succinic acid or anhydride and/or a fatty acid such as oleic acid with a polyamine.

Metal deactivators include derivatives of benzotriazoles (typically tolyltriazole), 1,2,4-triazoles, benzimidazoles, 2-alkyldithiobenzimidazoles or 2-alkyldithiobenzothiazoles. The metal deactivators may also be described as corrosion inhibitors.

Foam inhibitors Include copolymers of ethyl acrylate and 2-ethylhexyl acrylate and optionally vinyl acetate.

Demulsifiers include trialkyl phosphates, and various polymers and copolymers of ethylene glycol, ethylene oxide, propylene oxide, or mixtures thereof.

Pour point depressants including esters of maleic anhydride-styrene, polymethacrylates, polyacrylates or polyacrylamides.

Seal swell agents including Exxon Necton-37™ (FN 1380) and Exxon Mineral Seal Oil™ (FN 3200).

Preferably the lubricating oil composition contains co-solvents selected from the group consisting of di-isodecyl adipate, di-propyladipate, di-isotridecyl adipate, trimethylpropyl tricaprylate, di-isooctyl adipate, di-ethylhexyl adipate and d-inonyl adipate. Preferably the lubricating oil composition contains co-solvents in an amount of ≧0.5% to ≦35% by weight, more preferably ≧1% to ≦30% by weight, related to the overall weight of the lubricating oil composition.

In certain embodiments, the lubricating oil composition is an axle lubricating oil composition. In particular, the axle lubricating oil composition includes a polyalphaolefin having a kinematic viscosity at 100° C. of from 2 to 40 cSt when measured in accordance with ASTM D445. Alternatively, the polyalphaolefins may have a kinematic viscosity at 100° C. of from 5 to 40, from 5 to 35, from 5 to 30, from 5 to 25, from 5 to 20 or from 5 to 15, cSt. Alternatively, the polyalphaolefin may have a kinematic viscosity at 100° C. of from 2 to 35, from 2 to 30, from 2 to 25, from 2 to 20, from 2 to 15, from 2 to 10, from 10 to 30, or from 15 to 25, cSt.

In certain embodiments of the axle lubricating oil composition, the polyalphaolefin is present in an amount of from 20 to 60 parts by weight based on 100 parts by weight of the axle lubricating oil composition. Alternatively, the polyalphaolefins may be present in an amount of from 20 to 50, from 20 to 40, from 20 to 30, 30 to 60, from 40 to 60, from 50 to 60, or from 30 to 50, parts by weight based on 100 parts by weight of the axle lubricating oil composition.

The axle lubricating oil composition also includes the alkoxylated polytetrahydrofuran of general formula (II). It is to be appreciated that the axle lubricating oil composition may include any of the embodiments of the alkoxylated polytetrahydrofuran of general formula (II) as described above.

In certain embodiments of the axle lubricating oil composition, the alkoxylated polytetrahydrofuran of general formula (II) is present in an amount of from 10 to 40 parts by weight based on 100 parts by weight of said axle lubricating oil composition. Alternatively, the alkoxylated polytetrahydrofuran of general formula (II) is present in an amount of from 10 to 30, from 10 to 20, from 20 to 40, from 30 to 40, or from 20 to 30, parts by weight based on 100 parts by weight of the axle lubricating oil composition.

In certain embodiments, the axle lubricating oil composition has a KRL Shear loss after 200 hours of less than 8% when measured in accordance with CEC L-45-A-99. Alternatively, the axle lubricating oil composition has a KRL Shear loss after 200 hours of less than 7%, 6%, 5%, 4% or 3%, when measured in accordance with CEC L-45-A-99.

Like the lubricating oil composition described above, the axle lubricating oil composition may also include the carboxylic acid esters of Group V. In certain embodiments, the carboxylic acid ester is di-(2-propylheptyl)-adipate (DPHA). When included, the carboxylic acid ester may be present in an amount of from 5 to 20 parts by weight, based on 100 parts by weight of the axle lubricating oil composition.

In certain embodiments, the axle lubricating oil composition includes the alkoxylated polytetrahydrofuran of general formula (II) in an amount of from 10 to 40 parts by weight, the polyalphaolefin having a kinematic viscosity at 100° C. of from 2 to 40 cSt when measured in accordance with ASTM D445 in an amount of from 20 to 60 parts by weight, and the carboxylic acid ester in an amount of from 5 to 20 parts by weight, each based on 100 parts by weight of the axle lubricating oil composition. Although not required, the axle lubricating oil composition may have a KRL Shear loss after 200 hours of less than 8% when measured in accordance with CEC L-45-A-99.

Of course, the axle lubricating oil composition may include one or more of the performance additives described above. In particular, the axle lubricating oil composition may include co-solvents, dispersants, metal deactivators, detergents, viscosity modifiers, extreme pressure agents), antiwear agents, antioxidants, corrosion inhibitors, foam inhibitors, demulsifiers, pour point depressants, seal swelling agents, friction modifiers and mixtures thereof. When selected, the one or more performance additives are present in the amounts described above. Similarly, the axle lubricating oil composition may include one or more of the Group I-V base stocks described above.

Although not required, the axle lubricating oil composition typically has a kinematic viscosity at 100° C. of from 4 to 40 cSt when measured in accordance with ASTM D445. Alternatively, the axle lubricating oil composition has a kinematic viscosity at 100° C. of from 5 to 35, from 6 to 30, from 7 to 25, from 8 to 20, or from 9 to 15, cSt when measured in accordance with ASTM D445. In certain embodiments, the axle lubricating oil composition has a kinematic viscosity at 40° C. of from 40 to 110 cSt when measured in accordance with ASTM D445. Alternatively, the axle lubricating oil composition has a kinematic viscosity at 40° C. of from 45 to 100, from 50 to 90, or from 55 to 80, or from 60 to 70, cSt when measured in accordance with ASTM D445. It is to be appreciated that for the purpose of this disclosure, any reference to kinematic viscosity is the kinematic viscosity measured in accordance with ASTM D445.

As indicated by the kinematic viscosity values described above, the axle lubricating oil composition has an excellent viscosity index. Typically, the axle lubricating oil composition has a viscosity index of from 160 to 250 as measured in accordance with ASTM D2270. Alternatively, the axle lubricating oil composition may have a viscosity index of from 160 to 240, from 170 to 250, from 180 to 250, from 190 to 250, from 200 to 250, from 210 to 250, from 220 to 250, from 230 to 250, from 170 to 240, from 180 to 230, from 190 to 220, or from 200 to 210. It is to be understood that for the purpose of this disclosure, any reference to viscosity index is the viscosity index as measured by ASTM D2270.

The kinematic viscosity and the viscosity index of the axle lubricating oil composition results in the axle lubricating oil composition being particularly useful for lubricating an axle of a vehicle. In addition, the axle lubricating oil composition also has excellent frictional properties, as evidenced by the friction coefficients of the axle lubricating oil. In particular, in certain embodiments, the axle lubricating oil composition has a friction coefficient in the range of 0.003 to 0.030 at 25% slide roll ratio (SRR) determined using MTM measurements at 100° C. and 120° C. and 1 GPa.

Without being bound to any particular theory, it is believed that the blend of the alkoxylated polytetrahydrofuran of general formula II and the polyalphaolefin is especially suitable for axle lubricating oil compositions because the blend has excellent low and high temperature performance as evidenced by the viscosity index and also has excellent frictional properties as evidenced by the measured friction coefficients. In certain embodiments, the frictional properties translate into the axle lubricating oil composition improving the fuel efficiency of the vehicle. Those having ordinary skill in the art readily recognize that even a relatively small increase in fuel efficiency is extremely desirable.

In certain embodiments, the present invention is directed to a method of lubricating an axle of a vehicle for increasing the fuel efficiency of the vehicle. The method includes providing an axle lubricating oil composition. The axle lubricating oil composition may be any embodiment of the axle lubricating oil composition described above. In certain embodiments, the axle lubricating oil composition includes the polyalphaolefin having a kinematic viscosity at 40° C. of from 2 to 40 cSt when measured in accordance with ASTM D445 with the polyalphaolefin being present in an amount of from 30 to 60 parts by weight based on 100 parts by weight of the axle lubricating oil composition. The axle lubricating oil composition also includes an alkoxylated polytetrahydrofuran of general formula (II) present in an amount of from 20 to 40 parts by weight based on 100 parts by weight of the axle lubricating oil composition. The method also includes contacting the axle lubricating oil composition and the axle of the vehicle to lubricate the axle and increase the fuel efficiency of the vehicle. In certain embodiments, the axle lubricating oil composition has a KRL Shear loss after 200 hours of less than 8% when measured in accordance with CEC L-45-A-99. In addition, the axle lubricating oil composition may also have a friction coefficient in the range of 0.003 to 0.030 at 25% slide roll ratio (SRR) determined using MTM measurements at 100° C. and 120° C. and 1 GPa.

In another embodiment, the presently claimed invention is directed to a method of reducing friction in an engine using an engine oil comprising at least one alkoxylated polytetrahydrofuran as defined above or a mixture of polytetrahydrofurans as defined above.

In yet another embodiment, the presently claimed invention is directed to a method of enhancing the friction modification properties of a lubricating oil composition in the lubrication of a mechanical device comprising formulating said lubricating oil composition with at least one alkoxylated polytetrahydrofuran as defined above.

Enhancing the friction-modification properties means in the sense of the present invention that the friction coefficient of a lubricating oil composition comprising a carboxylic acid ester as defined above is lower than the friction coefficient of a lubricating oil composition that does not contain said carboxylic acid ester. The friction-modification properties are determined by measuring the friction coefficient at 25% slide roll ratio (SRR) using mini-traction machine (MTM) measurements at 70° C. and 1 GPa.

A mechanical device in the sense of the presently claimed invention is a mechanism consisting of a device that works on mechanical principles.

The mechanical device is preferably selected from the group consisting of bearings, gears, joints and guidances. Preferably the mechanical device is operated at temperatures in the range of ≧10° C. to ≦80° C.

EXAMPLES

OHZ=hydroxyl number, determined according to DIN 53240

Mn=number average molecular weight, determined according to DIN 55672-1 and referred to Polystyrene calibration standard.

Mw=weight average molecular weight, determined according to DIN 55672-1 and referred to Polystyrene calibration standard.

PD=polydispersity, determined according to DIN 55672-1

Measuring Physical Properties

The kinematic viscosity was measured according to the standard international method ASTM D 445.

The viscosity Index was measured according to the ASTM D 2270.

The pour point according was measured to DIN ISO 3016.

Friction Coefficient Evaluation

The fluids were tested in the MTM (Mini-Traction Machine) instrument using the so-called traction test mode. In this mode, the friction coefficient is measured at a constant mean speed over a range of slide roll ratios (SRR) to give the traction curve. SRR=sliding speed/mean entrainment speed=2 (U1−U2)/(U1+U2) in which U1 and U2 are the ball and disc speeds respectively

The disc and ball used for the experiments were made of steel (AISI 52100), with a hardness of 750 HV and Ra<0.02 μm. The diameter was 45.0 mm and 19.0 mm for the disc and the ball respectively. The tractions curves were run with 1.00 GPa contact pressure, 4 m/s mean speed and 70° C. temperature. The slide-roll ratio (SRR) was varied from 0 to 25% and the friction coefficient measured.

Oil Compatibility Evaluation

A method was developed in-house to determine oil compatibility. The oil and test material were mixed in 10/90, 50/50 and 90/10% w/w ratios respectively. The mixtures were mixed at room temperature by rolling for 12 hours. The mixtures' appearance was observed after homogenization and again after 24 hours. The test material is deemed compatible with the oil when no phase separation is observed after 24 hours for at least two of the ratios investigated.

Synthesis of the Polyalkylene Glycols Example 1 PolyTHF 650 with 20 Equivalents of C12 Epoxide

A steel reactor (1.5 l) was loaded with polytetrahydrofuran (MW 650) (0.2 mol, 130 g), and 3.4 g KOtBu was mixed and the reactor was purged with nitrogen. The reactor was heated under vacuum (10 mbar) and heated to 140° C. for 0.25 h. Then again nitrogen was loaded. At a pressure of 2 bar 50 g C12 epoxide was brought in dropwise at 140° C. 686 g C12 epoxide of total (736 g; 4.0 mol) was added during 10 h at 140° C. and under pressure of 6 bar. Yield: 874 g, quantitative (Theor.: 866 g) OHZ: 28.2 mg KOH/g.

Example 2 PolyTHF 650 with 12 Equivalents of C12 Epoxide and 20 Equivalents of Butylene Oxide (Block)

A steel reactor (1.5 l) was loaded with polytetrahydrofuran (MW 250) (0.2 mol, 130 g), and 3.4 g KOtBu was mixed and the reactor was purged with nitrogen. The reactor was heated under vacuum (10 mbar) and heated to 140° C. for 0.25 h. Then again nitrogen was loaded. At a pressure of 2 bar 50 g C12 epoxide was brought in dropwise at 140° C. 390 g C12 epoxide of total (441 g; 2.4 mol) was added during 5 h at 140° C. and under pressure of 6 bar. Then butylene oxide (288 g, 4.0 mol) was added within 4 h at 140° C. The reactor was stirred for 10 h at 140° C. and cooled to 80° C. The product was stripped by nitrogen. Then the product was discharged and mixed with Amboso® (magnesium silicate, 30 g) and mixed on a rotary evaporator at 80° C. The purified product was obtained by filtration in a pressure strainer (Filtrations media: Seitz 900). Yield: 866 g, quantitative (Theor.: 859 g) OHZ: 30.1 mg KOH/g

Example 3 PolyTHF 650 with 12 Equivalents of C12 Epoxide and 20 Butylene Oxide (Random)

A steel reactor (5 l) was loaded with polytetrahydrofuran (MW 250) (0.732 mol, 476 g), and KOtBu (12.6 g) was mixed and the reactor was purged with nitrogen. At a pressure of 2 bar a mixture of butylene oxide and C12 epoxide (14.64 mol, 1104 g butylene oxide; 8.8 mol, 1617 g C12 epoxide) was brought in dropwise during 30 h at 140° C. and under pressure of 6 bar. The reactor was stirred for 10 h at 140° C. and cooled to 80° C. The reactor was cooled to 80° C. and the product was stripped by nitrogen. Then the product was discharged and mixed with Ambosol® (magnesium silicate, 60 g) and mixed on a rotary evaporator at 80° C. The purified product was obtained by filtration in a pressure strainer (Filtrations media: Seitz 900). Yield: 3077 g (96%) (Th.: 3200 g), OHZ: 31.4 mg KOH/g

Example 4 PolyTHF 650 with 12 Equivalents of C12 Epoxide and 20 Equivalents of Propylene Oxide (Random)

A steel reactor (1.5 l) was loaded with polytetrahydrofuran (MW 650) (0.2 mol, 130 g), and KOtBu (3.21 g) was mixed and the reactor was purged with nitrogen. At a pressure of 2 bar a mixture of propylene oxide and C12 epoxide (4.0 mol, 232 g PO; 2.4 mol, 441 g C12 epoxide) was brought in dropwise during 7 h at 140° C. and under pressure of 6 bar. The reactor was stirred for 10 h at 140° C. and cooled to 80° C. The reactor was cooled to 80° C. and the product was stripped by nitrogen. Then the product was discharged and mixed with Ambosol® (magnesium silicate, 60 g) and mixed on a rotary evaporator at 80° C. The purified product was obtained by filtration in a pressure strainer (Filtrations media: Seitz 900). Yield: 800 g (quantitative) (Th.: 803 g), OHZ: 30.8 mgKOH/g.

Example 5 PolyTHF 1000 with 18 Equivalents of C12 Epoxide and 30 Equivalents of Butylene Oxide (Random)

A steel reactor (1.5 l) was loaded with polytetrahydrofuran (MW 1000) (0.1 mol, 100 g), and KOtBu (2.59 g) was mixed and the reactor was purged with nitrogen. At a pressure of 2 bar a mixture of butylene oxide and C12 epoxide (3.0 mol, 216 g butylene oxide; 1.8 mol, 331 g C12 epoxide) was brought in dropwise during 5 h at 140° C. and under pressure of 6 bar. The reactor was stirred for 10 h at 140° C. and cooled to 80° C. The reactor was cooled to 80° C. and the product was stripped by nitrogen. Then the product was discharged and mixed with Ambosol® (magnesium silicate, 60 g) and mixed on a rotary evaporator at 80° C. The purified product was obtained by filtration in a pressure strainer (Filtrations media: Seitz 900). Yield: 661 g (quantitative) (Th.: 647 g), OHZ: 24.7 mg KOH/g

Example 6 PolyTHF 1000 with 36 Equivalents of C12 Epoxide and 60 Equivalents of Butylene Oxide (Random)

A steel reactor (1.5 l) was loaded with polytetrahydrofuran (MW 1000) (0.1 mol, 100 g), and KOtBu (4.78 g) was mixed and the reactor was purged with nitrogen. At a pressure of 2 bar a mixture of butylene oxide and C12 epoxide (6.0 mol, 432 g butylene oxide; 3.6 mol, 662 g C12 epoxide) was brought in dropwise during 11 h at 140° C. and under pressure of 6 bar. The reactor was stirred for 10 h at 140° C. and cooled to 80° C. The reactor was cooled to 80° C. and the product was stripped by nitrogen. Then the product was discharged and mixed with Ambosol® (magnesium silicate, 60 g) and mixed on a rotary evaporator at 80° C. The purified product was obtained by filtration in a pressure strainer (Filtrations media: Seitz 900). Yield: 1236 g (quantitative) (Th.: 1194 g), OHZ: 9.4 mg KOH/g

Example 7A PolyTHF 650 with 4 Equivalents of C12 Epoxide and 40 Equivalents of Butylene Oxide (Random)

The oil compatibility and friction data are summarized in Table 2. The data demonstrate that the molecules derived from the present invention, namely polyalkylene glycols produced from the alkoxylation of polytetrahydrofuran (p-THF) with C12 epoxide show compatibility with mineral oils and low viscosity polyalphaolefins whilst providing low friction coefficients (50.025 at 25% SRR in MTM experiments).

Example 7B PolyTHF 1000 with 40 Equivalents of C₁₂ Epoxide and 70 Equivalents of Butylene Oxide (Random)

A steel reactor (1.5 l) was loaded with polytetrahydrofuran (MW 1000 g/mol, 63.7 mmol, 63.7 g) and CsOH (50% aqueous solution, 6.9 g). The mixture was dried under vacuum (<10 mbar) at 100° C. to a water content below 0.1% (Karl-Fischer titration). At a pressure of 2 bar nitrogen a mixture of butylene oxide and C12 epoxide (4.45 mol, 321 g butylene oxide; 2.55 mol, 469 g C12 epoxide) was brought in dropwise during 10 h at 130° C. The reaction mixture was stirred for 20 h at 130° C. and cooled to 80° C. Volatile compounds were removed by nitrogen stripping. Then the product was discharged and mixed with Ambosol® (13 g) and mixed on a rotary evaporator at 80° C. for 2 h. The purified product was obtained by filtration in a pressure strainer (Filtrations media: Seitz 900).

Yield: 850 g, OHZ: 11.7 mg KOH/g, M_(w): 10617 g/mol and Ma: 8356 g/mol, polydispersity: 1.27.

Oil compatible materials presented in Examples 1 to 7a consistently exhibit friction coefficient equal or lower than 0.025 at 25% SRR in the MTM experiments.

TABLE 1 OHZ Starting Random/ C12 [mgKOH/ alcohol Block PO BuO epoxide g] Mn Mw PD Example 1 pTHF 650 block 20 28.2 4517 4923 1.1 Example 2 pTHF 650 block: 1. 20 12 30.1 3861 4602 1.2 C12 epoxide, 2. BuO Example 3 pTHF 650 random 20 12 31.4 4720 4650 1.4 Example 4 pTHF 650 random 20 12 30.8 4660 5074 1.1 Example 5 pTHF 1000 random 30 18 24.7 4551 5667 1.2 Example 6 pTHF 1000 random 60 36 9.4 5204 6629 1.3 Example 7A pTHF 650 block 40 4 27 4872 5369 1.1 Comparative examples Example 8* polybutylene glycol (propandiol + 43 BO) Example 9* p-THF 1000 + 20 PO Example 10* p-THF 1000 + 10 PO + 13 EO Example 11* p-THF 250 Example 12* p-THF 650 Example 13* p-THF 1000

TABLE 2 Mineral Low MTM oil Group III viscosity PAO Kinematic friction compatibility at compatibility at viscosity Vis- Pour coefficient room temperature room temperature (mm2/s) cosity point at (oil/test material) (oil/test material) 40° C. 100° C. Index (° C.) 25% SSR 10/90 50/50 90/10 10/90 50/50 90/10 Ex. 1 289 40 192 12 0.015 Yes Yes Yes No Yes Yes Example 2 284 37 182 −11 0.02 Yes Yes Yes Yes Yes Yes Example 3 392 50 189 −42 0.019 Yes Yes Yes Yes Yes Yes Example 4 268 38 195 −35 -0.016 Yes Yes Yes Yes Yes Yes Example 5 412 52 191 −43 0.018 Yes Yes Yes Yes Yes Yes Example 6 441 56 195 −39 0.019 Yes Yes Yes Yes Yes Yes Example 7A 539 64 192 −42 0.022 Yes Yes Yes — — — Comparative examples Example 8* 304 35 159 −39 0.034 Yes Yes Yes No No No Example 9* 348 50 207 −9 0.013 No No No No No No Example 10* 359 57 227 −6 0.008 No No No No No No Example 11* 54 7 94 −42 0.007 No No No No No No Example 12* 159 22 165 3 0.007 No No No No No No Example 13* 291 40 193 6 0.007 No No No No No No

An axle lubricating oil composition within the scope of the invention is provided below in Table 3 as Example 14. Table 3 also includes a comparative axle lubricating oil composition as Example 15*. Each individual component for Example 14 and 15 in Table 3 is provided in parts by weight based on 100 parts by weight of the respective example.

TABLE 3 Example 14 Example 15* Base oil 1 25 — Base oil 2 — 25 Base oil 3 75 75 Kinematic Viscosity 40° C. 14.12 14.28 (ASTM D445) (cSt) Kinematic Viscosity 100° C. 81.26 88.94 (ASTM D445) (cSt) Viscosity Index 181 167 (ASTM D2270)

Base oil 1 is an alkoxylated polytetrahydrofuran of general formula (II).

Base oil 2 is a metallocene catalyzed polyalphaolefin base oil commercially available from ExxonMobil having a kinematic viscosity at 100° C. of 150 cSt.

Base oil 3 is a polyalphaolefin base oil having a kinematic viscosity at 100° C. of 6 cSt.

The viscosity profiles of Example 14 and Example 15* were evaluated by measuring the kinematic viscosities at 40° C. and 100° C. and calculating the viscosity index. The results of this testing are provided in Table 3. The kinematic viscosity and viscosity index data demonstrate that Example 14 has superior low and high temperature properties relative to Example 15*. In addition, the friction coefficients of Examples 14 and 15* were measured using MTM at 120° C. and 1 GPa with varying slide roll ratios. The friction coefficients are provided in FIG. 1. The results demonstrate that Example 14 has a lower friction coefficient in comparison to Example 15*. Thus, Example 14 is more fuel efficient than Example 15*.

Additional examples of the axle lubricating oil composition within the scope of the invention are provided below in Table 4 as Examples 16-18. Table 4 also includes a comparative axle lubricating oil composition as Example 19*. Each individual component for Examples 16-18 and Example 19* in Table 4 is provided in parts by weight based on 100 parts by weight of the respective example.

TABLE 4 Example Example Example Example 16 17 18 19* Base oil 4 28 28 29 — Base oil 5 — — — 28.6 Base oil 6 43.8 45.8 45.8 — Base oil 7 — — — 42.6 Additive package 1 10 — 10 10 Additive package 2 — 8 — — Carboxylic acid ester 1 15 15 12 15 Antioxidant 1 0.5 0.5 0.5 — Antioxidant 2 0.5 0.5 0.5 — Antioxidant 3 — — — 0.9 Dispersant 1 2.0 2.0 2.0 — Dispersant 2 — — — 2.0 Defoamer 1 0.2 0.2 0.2 0.2

Base oil 4 is an alkoxylated polytetrahydrofuran of general formula (II).

Base oil 5 is a metallocene catalyzed polyalphaolefin base oil commercially available from ExxonMobil having a kinematic viscosity at 100° C. of 150 cSt.

Base oil 6 is a polyalphaolefin base oil having a kinematic viscosity at 100° C. of 4 cSt.

Base oil 7 is a polyalphaolefin base oil having a kinematic viscosity at 100° C. of 6 cSt.

Additive package 1 is a commercially available additive package under the tradename ANGLAMOL® from the Lubrizol Corporation.

Additive package 2 is a commercially available additive package under the tradename HITEC® from the Afton Chemical Corporation.

Carboxylic acid ester 1 is DPHA.

Antioxidant 1 is a commercially available antioxidant under the tradename IRGANOX® from the BASF Corporation.

Antioxidant 2 is an antioxidant different from Antioxidant 1 and is also commercially available under the tradename IRGANOX® from the BASF Corporation.

Antioxidant 3 is phenyl-alpha-naphthylamine.

Dispersant 1 is a commercially available dispersant under the tradename HITEC® from the Afton Chemical Corporation

Dispersant 2 is a commercially available borated dispersant under the tradename HITEC® from the Afton Chemical Corporation.

Defoamer 1 is a nonionic surfactant commercially available under the tradename SYNATIVE AC AMH 2® from the BASF Corporation.

The viscosity profiles of Examples 16-18 and Example 19* were evaluated by measuring the kinematic viscosities at 40° C. and 100° C. and calculating the viscosity index. Additionally, the shear stability of Examples 16-18 and Example 19* was evaluated by measuring the KRL Shear Loss according to CEC L-45-A-99. The results of this testing are provided below in Table 5.

TABLE 5 Kinematic Viscosity (D445) (cSt) Viscosity Index KRL Shear Loss 40° C. 100° C. (D2270) (%) Example 16 67.15 12.76 193 1.1 Example 17 72.82 13.54 192 4.9 Example 18 66.46 12.60 193 — Example 19* 77.19 12.87 168 1.2

As shown in Table 5, Examples 16-18 have greater low and high temperature performance in comparison to Example 19* as evidenced by the viscosity index values. In addition, Examples 16 and 17 demonstrate excellent shear stability as evidenced by the KRL Shear Loss values.

The oxidative stability of Examples 16 and 17 and Example 19* was evaluated by measuring the L-60 Oxidation/Thermal Stability at 200 hours in accordance with ASTM D5704. The results of this testing are displayed in Table 6.

TABLE 6 L-60 Oxidation/Thermal Stability at 200 hours Viscosity Increase, Pentane Tolune Carbon/ Sludge 100° C. Insolubles Insolubles Varnish (10 = (%) (wt. %) (wt. %) (10 = clean) clean) Example 16 25 0.1 0.0 9.2 9.7 Example 17 3 0.1 0.1 8.9 9.6 Example 19* 36 0.3 0.2 8.8 9.6

As shown in Table 6, Examples 16 and 17 demonstrate superior oxidation performance in comparison to Example 19* as indicated by the relatively lower increase in viscosity after 200 hours of testing. This superior performance is also observable by contrasting the carbon/varnish and sludge values of Examples 16 and 17 with the corresponding values for Example 19*.

Example 18 and Example 19* were also evaluated for fuel efficiency in accordance with EPA 75/25 (both city and highway simulations) and European New European Drive Cycle (NEDC) on a chassis dynamometer using a 2015 Dodge Ram truck (C 235 axle). The data generated from this testing can be found in FIGS. 2A-2C, as a percentage increase in comparison to a conventional SAE 75W-140 lubricant. As shown in FIG. 2, Example 18 substantially out performed Example 19* in terms of fuel efficiency in both the EPA 75/25 and NEDC testing. Persons having ordinary skill in the art appreciate that EPA 75/25 and NEDC are industry recognized test methods for determining fuel efficiency. 

1. An axle lubricating oil composition comprising: (i) a polyalphaolefin having a kinematic viscosity at 100° C. of from 2 to 40 cSt when measured in accordance with ASTM D445, with said polyalphaolefin being present in an amount of from 20 to 60 parts by weight based on 100 parts by weight of said axle lubricating oil composition; and (ii) an alkoxylated polytetrahydrofuran of general formula (II) present in an amount of from 10 to 40 parts by weight based on 100 parts by weight of said axle lubricating oil composition

wherein, m is an integer in the range of ≧1 to ≦50, m′ is an integer in the range of ≧1 to ≦50, (m+m′) is an integer in the range of ≧1 to ≦90, n is an integer in the range of ≧0 to ≦75, n′ is an integer in the range of ≧0 to ≦75, p is an integer in the range of ≧0 to ≦75, p′ is an integer in the range of ≧0 to ≦75, k is an integer in the range of ≧2 to ≦30, R¹ denotes an unsubstituted, linear or branched, alkyl radical having 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27 or 28 carbon atoms, R² denotes —CH₂—CH₃, R³ is identical or different and denotes a hydrogen atom or —CH₃, and wherein the concatenations denoted by k are distributed to form a block polymeric structure and the concatenations denoted by p, p′, n, n′, m and m′ are distributed to form a block polymeric structure or a random polymeric structure.
 2. The axle lubricating oil composition according to claim 1 wherein said polyalphaolefin has a kinematic viscosity at 100° C. of from 2 to 10 cSt when measured in accordance with ASTM D445, with said polyalphaolefin being present in an amount of from 40 to 50 parts by weight based on 100 parts by weight of said axle lubricating oil composition.
 3. The axle lubricating oil composition according to claim 2 further comprising a carboxylic acid ester in an amount of from 5 to 20 parts by weight based on 100 parts by weight of said axle lubricating oil composition.
 4. The axle lubricating oil composition according to claim 1 wherein k is an integer in the range of ≧3 to ≦25.
 5. The axle lubricating oil composition according to claim 1 wherein k is an integer in the range of ≧5 to ≦20, and wherein (m+m′) is in the range of ≧3 to ≦65.
 6. The axle lubricating oil composition according to claim 1, wherein the alkoxylated polytetrahydrofuran has a weight average molecular weight in the range of 4000 to 7000 g/mol determined according to DIN 55672-1 (polystyrene calibration standard), and wherein the ratio of (m+m′) to k is in the range of 0.3:1 to 6:1.
 7. The axle lubricating oil composition according to claim 3 having a KRL Shear loss after 200 hours of less than 8% when measured in accordance with CEC L-45-A-99.
 8. The axle lubricating oil composition according to claim 1 wherein R¹ denotes an unsubstituted, linear alkyl radical having 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 or 18 carbon atoms.
 9. The axle lubricating oil composition according to claim 1, wherein; m is an integer in the range of ≧1 to ≦30, m′ is an integer in the range of ≧1 to ≦30, (m+m′) is an integer in the range of ≧3 to ≦50, n is an integer in the range of ≧0 to ≦45, n′ is an integer in the range of ≧0 to ≦45, p is an integer in the range of ≧3 to ≦45, p′ is an integer in the range of ≧3 to ≦45, (p+p′) is an integer in the range of ≧6 to ≦90, k is an integer in the range of ≧3 to ≦25, R¹ denotes an unsubstituted, linear alkyl radical having 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 or 18 carbon atoms, R² denotes —CH₂—CH₃, and R³ denotes —CH₃.
 10. An axle lubricating oil composition comprising: (i) a polyalphaolefin having a kinematic viscosity at 100° C. of from 2 to 40 cSt when measured in accordance with ASTM D445; and (ii) an alkoxylated polytetrahydrofuran of general formula (II)

wherein, m is an integer in the range of ≧1 to ≦50, m′ is an integer in the range of ≧1 to ≦50, (m+m′) is an integer in the range of ≧1 to ≦90, n is an integer in the range of ≧0 to ≦75, n′ is an integer in the range of ≧0 to ≦75, p is an integer in the range of ≧0 to ≦75, p′ is an integer in the range of ≧0 to ≦75, k is an integer in the range of ≧2 to ≦30, R¹ denotes an unsubstituted, linear or branched, alkyl radical having 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27 or 28 carbon atoms, R² denotes —CH₂—CH₃, R³ is identical or different and denotes a hydrogen atom or —CH₃, and wherein the concatenations denoted by k are distributed to form a block polymeric structure and the concatenations denoted by p, p′, n, n′, m and m′ are distributed to form a block polymeric structure or a random polymeric structure; and wherein said axle lubricating oil composition has a KRL Shear loss after 200 hours of less than 8% when measured in accordance with CEC L-45-A-99.
 11. The axle lubricating oil composition according to claim 10 wherein said polyalphaolefin has a kinematic viscosity at 100° C. of from 2 to 10 cSt when measured in accordance with ASTM D445, with said polyalphaolefin being present in an amount of from 40 to 50 parts by weight based on 100 parts by weight of said axle lubricating oil composition.
 12. The axle lubricating oil composition according to claim 11 further comprising a carboxylic acid ester base stock in an amount of from 5 to 20 parts by weight based on 100 parts by weight of said axle lubricating oil composition.
 13. The axle lubricating oil composition according to claim 10 wherein k is an integer in the range of ≧3 to ≦25.
 14. The axle lubricating oil composition according to claim 10 wherein k is an integer in the range of ≧5 to ≦20, and wherein (m+m′) is in the range of ≧3 to ≦65.
 15. The axle lubricating oil composition according to claim 10, wherein the alkoxylated polytetrahydrofuran has a weight average molecular weight in the range of 4000 to 7000 g/mol determined according to DIN 55672-1 (polystyrene calibration standard), and wherein the ratio of (m+m′) to k is in the range of 0.3:1 to 6:1.
 16. The axle lubricating oil composition according to claim 12 having a KRL Shear loss after 200 hours of less than 8% when measured in accordance with CEC L-45-A-99.
 17. The axle lubricating oil composition according to claim 10 wherein R¹ denotes an unsubstituted, linear alkyl radical having 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 or 18 carbon atoms.
 18. The axle lubricating oil composition according to claim 10, wherein; m is an integer in the range of ≧1 to ≦30, m′ is an integer in the range of ≧1 to ≦30, (m+m′) is an integer in the range of ≧3 to ≦50, n is an integer in the range of ≧0 to ≦45, n′ is an integer in the range of ≧0 to ≦45, p is an integer in the range of ≧3 to ≦45, p′ is an integer in the range of ≧3 to ≦45, (p+p′) is an integer in the range of ≧6 to ≦90, k is an integer in the range of ≧3 to ≦25, R¹ denotes an unsubstituted, linear alkyl radical having 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 or 18 carbon atoms, R² denotes —CH₂—CH₃, and R³ denotes —CH₃.
 19. A method of lubricating an axle of a vehicle for increasing the fuel efficiency of the vehicle, said method comprising: providing an axle lubricating oil composition comprising; (i) a polyalphaolefin having a kinematic viscosity at 40° C. of from 2 to 40 cSt when measured in accordance with ASTM D445, with said polyalphaolefin being present in an amount of from 30 to 60 parts by weight based on 100 parts by weight of said axle lubricating oil composition; and (ii) an alkoxylated polytetrahydrofuran of general formula (II) present in an amount of from 20 to 40 parts by weight based on 100 parts by weight of said axle lubricating oil composition

wherein, m is an integer in the range of ≧1 to ≦50, m′ is an integer in the range of ≧1 to ≦50, (m+m′) is an integer in the range of ≧1 to ≦90, n is an integer in the range of ≧0 to ≦75, n′ is an integer in the range of ≧0 to ≦75, p is an integer in the range of ≧0 to ≦75, p′ is an integer in the range of ≧0 to ≦75, k is an integer in the range of ≧2 to ≦30, R¹ denotes an unsubstituted, linear or branched, alkyl radical having 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27 or 28 carbon atoms, R² denotes —CH₂—CH₃, R³ is identical or different and denotes a hydrogen atom or —CH₃, and wherein the concatenations denoted by k are distributed to form a block polymeric structure and the concatenations denoted by p, p′, n, n′, m and m′ are distributed to form a block polymeric structure or a random polymeric structure; and contacting the axle lubricating oil composition and the axle of the vehicle to lubricate the axle and increase the fuel efficiency of the vehicle.
 20. The method as set forth in claim 19 wherein the axle lubricating oil composition has a KRL Shear loss after 200 hours of less than 8% when measured in accordance with CEC L-45-A-99. 